The book "Enterococcus and Safety" is presented as a journey to the enterococcal world. The genus Enterococcus comprises a wide variety of both pathogenic and commensal gram-positive bacteria. These micro-organisms are common constituents of fermented products such as traditionally manufactured cheeses and dry sausages, in which it is believed that they contribute to the development of organoleptic characteristics. In addition, enterococci are also used to extend the shelf life and improve the hygienic safety of foodstuffs because they produce bacteriocins which may have a promising potential in bio-preservation and in the enhancement of the hygienic quality of food products. However, in recent years enterococci have emerged as serious pathogens in hospital environments, where vancomycin-resistant strains are gaining major importance. This dual role of enterococci as beneficial organisms or opportunistic pathogens leads to an increasing need for studies intended to discriminate between food-grade and pathogenic strains.